Determining the refractive index and average thickness of AsSe semiconducting glass films from wavelength measurements only

The dispersive refractive index n(λ) and thickness d of chalcogenide glass thin films are usually calculated from measurements of both optical transmission and wavelength values. Many factors can influence the transmission values, leading to large errors in the values obtained for n(λ) and d. Anovel optical method is used to derive n(λ) and d for AsSe semiconducting glass thin films deposited by thermal evaporation in the spectral region where k(2) « n(2), using only wavelength values. This entails obtaining two transmission spectra: one at normal incidence and another at oblique incidence. The procedure yields values for the refractive index and average thickness of thermally evaporated chalcogenide films to an accuracy better than 3%.